Seismic response of an 8-story RC-building from ambient vibration analysis

Abstract

In this study, we assess the dynamic characteristics of a 8-story RC-building composed by two units connected through a structural joint. This building, belonging to one of the largest hospitals in northern Greece, has been selected in the framework of an European funded project (REAKT) as test site for developing a Structural Health Monitoring system and it is instrumented with a permanent strong motion network. The assessment of the dynamic characteristics is performed using ambient vibration recorded by a temporary seismic network installed inside the structure. Non-parametric identification methods, namely the Peak Picking and Frequency Domain decomposition, are applied to perform operational modal analysis and extract the natural frequencies and mode shapes of the structural system. Since the detection of changes in the shear wave velocity inside the building is relevant for Health Monitoring analysis, we use the ambient vibration recordings to perform a deconvolution interferometry. Moreover, a shear-beam model is considered to estimate the velocity in the first three floors, where the distribution of internal sources introduces complex patterns in the impulse response functions. The velocity for lowest part of the building is estimated by optimizing the match between the arrival times of the empirical and theoretical pulses. Finally, the velocities and quality factors estimated from ambient vibration analysis are consistent with preliminary results obtained analyzing earthquake data recorded in the same building.

On‐Site Early Warning and Rapid Damage Forecasting Using Single Stations: Outcomes from the REAKT Project

“…First, we consider recordings made by the permanent SOSEWIN installations of the GFZ (e.g., Bishkek, Kyrgyzstan; Thessaloniki, Greece; Istanbul, Turkey; http:// lhotse21.gfz-potsdam.de/nagvis/frontend/nagvis-js/index.php, last accessed July 2015). Second, new installations were carried out to improve upon the number of SOSEWIN test sites and their associated recordings (Bindi, Petrovic, et al, 2015;Picozzi et al, 2015). Third, data from previous temporary field campaigns that involve the rapid deployment of SOSEWIN units have been collected (Picozzi et al, 2011).…”

“…(Bindi, Petrovic, et al, 2015), where we will present results obtained for two stations of the network. 3.…”

“…These values, although performing well in the cases analyzed in this study, might not be generally valid and therefore each individual station would need to be assessed and the relevant parameters calibrated, depending on the local noise conditions, the range of expected magnitudes, and epicentral distances of damaging events. The original record (collected by a high-quality permanent installation) has been contaminated with signal noise recorded by a temporary SO-SEWIN station installed in the AHEPA hospital (Bindi, Petrovic, et al, 2015) in Thessaloniki (Greece) to simulate the acquisition data using a low-cost system (i.e., the sensing nodes deployed as part of the SOSEWIN system) in a noisy urban environment. We used this Italian data because there are no records of large earthquakes at a close distance recorded by the SOSEWIN networks.…”

“…The event detection based on the above-mentioned criteria was tested over a period of one week (6-13 October 2013) of SOSEWIN recordings collected by two stations inside the AHEPA hospital (one installed at the top of the building and the other on the first floor, and therefore characterized by different levels and types of noise) within the framework of the REAKT project. These stations have been collecting seismic noise and earthquake data in continuous mode since their installation in 2012 (Karapetrou et al, 2014;Bindi, Petrovic, et al, 2015). Unfortunately, no recordings with the SOSEWIN system were available in the free field and, therefore, we have no signals recorded by these instruments that are not biased by the influence of the propagation of seismic waves within a building (Fig.…”

Seismic‐Wave Propagation in Shallow Layers at the GONAF‐Tuzla Site, Istanbul, Turkey

“…It is applied, for example, for imaging purposes (Vasconcelos and Snieder, 2008b), retrieving building response to ground shaking (Snieder and Şafak, 2006;Bindi et al, 2015), and for determining near-surface velocities (van Vossen et al, 2004;Parolai et al, 2009;Nakata and Snieder, 2012). Deconvolution interferometry has also found applications in estimating site-specific Q values.…”